Island Patterns

Thoughts

1. Looking for unique species of plants at remote areas (Siwa, Aswan, Sinai).
2. White people in South Africa, how about those as 'founder populations'? How about White people in Australia, in North America?
3. I do not buy the idea that mutations are accidental! I only see it 'polite' way of saying that science has yet to discover the patterns by which mutations happen to serve a non-accidental evolution purpose.
4. I do not agree that species are not perfectly adapted to their environments. I sense that there is something wrong with that. I believe species are indeed most perfectly adapted to their current natural environments. Or what?
5. I see the events in history that result in the creation of islands or separation of land are no accident. I see them as natural developments that take place within grand patterns to serve a purpose.
6. My comments above about refusing the thought of accidents, and imperfection might sound unscientific, yet I believe science might prove them one day. Science, to me, is not and should not be the only source of knowledge and it can be guided and inspired by other sources of knowledge.

Digest

• Drosophila species (fruit flies): 1500 worldwide, 500 in Hawaiian islands, 100 picture-winged
• endemic: species found in only one area
• Dispersion of ancestor species (founder population) into new locations and isolation of such locations (such as isolated islands) allow forces natural selection to evolve them into new species
• Natural selection is confined to the gene pool of the ancestors save only for occasional rare mutations
• The lineages through which the Drosophila species have evolved can be traced by analyzing the banding patterns on the chromosomes in the salivary glands of the their larvae
• The oldest islands have the first ancestors while the newest formed islands have the most recently evolved species
• Island biotas illustrate that:
• there is a historical element in the match between organisms and environments
• there is not just one perfect organism for each type of environment

Drosophila

Questions

1. How do islands form?
2. How do species specialize and evolve on an isolated island?

Genetic Polymorphism

Thoughts

When selecting a plant from its natural habitat, say from Aswan, to transplant elsewhere, it is a good idea to select from a location that would provide the characteristics you desire in the plant (ex: lower elevation to be more drought tolerant ... etc.)

Digest

• "The distinction between local ecotypes and polymorphic populations is not always a clear one."
• Genetic polymorshipsm was defined by Edmund Brisco Ford in 1940 as: "the occurrence together in the same habitat of two or more discontinuous forms of a species in such proportions that the rarest of them cannot merely be maintained by recurrent mutation or immigration".
• Transient polymorphisms occur when conditions in a habitat change so that one form is being replaced by another.
• In contrast to transient polymorphism, many polymorphisms are actively maintained in a population by natural selection, and there are a number of ways in which this may occur:
• Heterozygotes may be of superior fitness, but continually generate less fit homozygotes within the population
• Presence of gradients of selective forces favoring one morph at one end of the gradient and another form at the other
• There may be frequency-dependent selection in which each of the morphs of a species is fittest when it is rarest
• Selective forces may operate in different directions within different patches in the population

Questions

1. What is the difference between polymorphism and ecotypes?
2. What is polymorphism?
3. What are ecotypes?